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11.
Aurora González-Portal F. Bermejo-Martínez C. Baluja-Santos María Cristina Diez-Rodríguez 《Microchemical Journal》1985,31(3):368-374
A new method for the Spectrophotometric determination of bismuth using N-(2-acetamido)iminodiacetic acid as complexometric agent is proposed. The complex is formed in a wide pH range, 5.5–7.5, and has a maximum absorption at 265 nm. Beer's law is obeyed in the interval 3.8–17.9 μg of bismuth(III)/ml, with a minimum photometric error of 2.3. The molar absorptivity is 9.1 × 103 liters/cm mol. The stoichiometry of the reaction takes place in the metal-to-ligand ratio 1:2. The interferences produced by the more common ions are studied. The method has been successfully applied to the determination of bismuth in pharmaceutical formulations. 相似文献
12.
α-(1-adamantyl)-β-diketones are now accessible by the alkylation of Co(II) complexes of β-diketones with 1-bromoadamantane. The intermediacy of adamantyl cation is proposed. Co(II), Co(III) and Zn(II) complexes of pentane-2,4-dione react with alkyl halides precursors of stabilized carbenium ions, to give 3-alkylpentane-2,4-diones. 相似文献
13.
R. González-Ramírez H. Jiménez-Domínguez O. Solorza-Feria E. Ordóñez-Regil A. Cabral-Prieto S. Bulbulian 《Journal of Radioanalytical and Nuclear Chemistry》1993,174(2):291-298
Conditions for the electrodeposition of59Co and57Co on stainless steel foils have been studied. A set of electrolytic parameters has been determined to get a reasonably good electrodeposited sample. The57Co electrodeposited foil was then introduced in a quartz tube to be annealed in an argon flow. The final product was a 11 Ci Mössbauer source for college experiments which was succesfully tested by obtaining spectra of stainless steel and sodium nitroprusside. 相似文献
14.
We report molecular dynamics computer simulations of the surface tension and interfacial thickness of ionic liquid-vapor interfaces modeled with a soft core primitive model potential. We find that the surface tension shows an anomalous oscillatory behavior with interfacial area. This observation is discussed in terms of finite size effects introduced by the periodic boundary conditions employed in computer simulations. Otherwise we show that the thickness of the liquid-vapor interface increases with surface area as predicted by the capillary wave theory. Data on the surface tension of size-asymmetric ionic liquids are reported and compared with experimental data of molten salts. Our data suggest that the surface tensions of size-asymmetric ionic liquids do not follow a corresponding states law. 相似文献
15.
González-Bravo L Marrero-Delange D González-Guevara JL 《Journal of chromatography. A》2000,888(1-2):159-173
The method's accuracy of a compound quantitation by chromatography depends on the calibration procedure with a pure standard of the target analyte, if the latter is unavailable uncertainty is unavoidable. The group method is a different approach in GC quantitative analysis that shows a practicable way for avoiding this uncertainty and accurately quantify a mixture containing one or more unavailable components. This paper is concerned with the definition of the group method quantitative parameters, the application procedures for their calculation, the determination of the quantitative proportion of a group of unavailable components of a mixture and the partial or total quantitation of the latter. The paper also describes the steps for carrying out the so-called group-correlation method in the determination of the response factors of unavailable compounds, which belong to a homologous series. The GC experimental corroboration of the group method approach employing model mixtures of compounds is also presented. 相似文献
16.
Marchante-Gayón JM González JM Fernández ML Blanco E Sanz-Medel A 《Analytical and bioanalytical chemistry》1996,355(5-6):615-622
A novel High Performance Liquid Chromatography (HPLC) method for the separation of selenium species with specific detection by off-line Electrothermal Atomization Atomic Absorption Spectrometry (ETAAS) or on-line focused microwave digestion (MW) Hydride Generation Atomic Absorption Spectrometry (HG-AAS) is described. Vesicular mobile phases of the cationic surfactant didodecyldimethylammonium bromide (DDAB) have been evaluated for the liquid chromatographic separation of inorganic selenium (selenite and selenate) and different selenoaminoacids (selenocystine, selenomethionine and selenoethionine) on a C(18) reversed-phase column modified by DDAB molecules. The effects of different parameters (pH, buffer and vesicle concentrations) of the mobile phase on the retention times have been determined. The detection limit for selenium with the proposed off-line HPLC-ETAAS method has been found to be 5 microg/L of Se. The detection limit using HPLC-"on line" focused microwave digestion-HG-AAS has been found to be 1 microg/L of Se, with a precision (repeatability) better than +/- 5%. The latter proved to be an exceptional on-line real-time chromatographic detector for selenium speciation purposes. 相似文献
17.
The two new diterpenes, vierol (1) [(?)kaurane-16α,18-diol] and powerol (3) [(?)kaurane-7β,16α-diol] have been isolated from Sideritis canariensis Ait. 1 was obtained by partial synthesis from epicandicandiol (7), and 3 was related with (?)kauranol (6) and (?)kauren-7β-ol acetate (11). Reduction of the acetoxy-aldehyde 14 by the method of Huang-Minlon and posterior acetylation gave 11, (?)isokauren-7β-ol acetate (17) and (?)kauran-7β-ol acetate (18). 相似文献
18.
Ernesto R. González 《Journal of Electroanalytical Chemistry》1978,90(3):431-438
The adsorption of azide ions on mercury from aqueous solutions of NaN3+NaF at constant ionic strength has been studied by measurements of the double layer capacity. Taking into account changes in the structure of the diffuse layer, it was possible to show that the properties of the inner layer are similar to those observed previously in solutions of pure NaN3, and that the same adsorption isotherm applies to both systems. 相似文献
19.
Preparation and sedimentation behavior in magnetic fields of magnetite-covered clay particles 总被引:4,自引:0,他引:4
Galindo-González C de Vicente J Ramos-Tejada MM López-López MT González-Caballero F Durán JD 《Langmuir : the ACS journal of surfaces and colloids》2005,21(10):4410-4419
This work is devoted to the preparation of magnetite-covered clay particles in aqueous medium. For this purpose, magnetite nanoparticles were synthesized by a coprecipitation method. These magnetic particles are adhered to sodium montmorillonite (NaMt) particles in aqueous suspensions of both materials, by appropriate control of the electrolyte concentrations. The best condition to produce such heteroaggregation corresponds to acid pH and approximately 1 mol/L ionic strength, when the electrokinetic potentials (zeta-potential) of both NaMt and Fe3O4 particles have high enough and opposite sign, as demonstrated from electrophoresis measurements. When a layer of magnetite re-covers the clay particles, the application of an external magnetic field induces a magnetic moment in clay-magnetite particles parallel to the external magnetic flux density. The sedimentation behavior of such magnetic particles is studied in the absence or presence of an external magnetic field in a vertical direction. The whole sedimentation behavior is also strongly affected by the formation of big flocculi in the suspensions under the action of internal colloidal interactions. van der Waals and dipole-dipole magnetic attractions between magnetite-covered clay particles dominate the flocculation processes. The different relative orientation of the clay-magnetite particles (edge-to-edge, face-to-edge, and face-to-face) are discussed in order to predict the most favored flocculi configuration. 相似文献
20.
López-Hernández J González-Castro MJ Pereda-González M 《Journal of chromatographic science》2000,38(9):383-385
A high-performance liquid chromatographic method using refractive index detection for the determination of glycogen in sea urchin (Paracentrotus lividus) gonads is developed. After alkaline digestion with sodium carbonate, samples are adjusted to pH 4.6 with citric acid and incubated with amyloglucosidase to hydrolyze the glycogen. The resulting glucose is determined using a Spherisorb NH2 column as the stationary phase and an acetonitrile-water mixture (80:20, v/v) as the mobile phase. The relative standard deviation (%) was 3.57, the limit of detection was 40.1 microg/mL, and the recovery percentage was 97.2%. 相似文献